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<H2><A NAME="SECTION03223000000000000000"></A><A NAME="subsecnaming"></A><A NAME="1190"></A>
<BR>
Naming Scheme
</H2>

<P>
The name of each LAPACK routine is a coded specification of
its function (within the very tight limits of standard Fortran 77
6-character names).

<P>
All driver and computational routines<A NAME="1191"></A> have names
of the form <B>XYYZZZ</B>, where for
some driver routines the 6th character is blank.

<P>
The first letter, <B>X</B>, indicates the data type as follows:

<P>
<BLOCKQUOTE>
<TABLE CELLPADDING=3>
<TR><TD ALIGN="LEFT">S</TD>
<TD ALIGN="LEFT">REAL</TD>
</TR>
<TR><TD ALIGN="LEFT">D</TD>
<TD ALIGN="LEFT">DOUBLE PRECISION</TD>
</TR>
<TR><TD ALIGN="LEFT">C</TD>
<TD ALIGN="LEFT">COMPLEX</TD>
</TR>
<TR><TD ALIGN="LEFT">Z</TD>
<TD ALIGN="LEFT">COMPLEX*16  or DOUBLE COMPLEX</TD>
</TR>
</TABLE>
</BLOCKQUOTE>

<P>
When we wish to refer to an LAPACK routine generically, regardless
of data type, we replace the first letter by ``x''. Thus xGESV refers
to any or all of the routines SGESV, CGESV, DGESV and ZGESV.

<P>
The next two letters, <B>YY</B>, indicate the type of matrix (or
of the most significant matrix).
Most of these two-letter codes apply to both real and complex matrices;
a few apply specifically to one or the other, as indicated in Table
<A HREF="node24.html#tabtypes">2.1</A>.

<P>
<BR>
<DIV ALIGN="CENTER">

<A NAME="tabtypes"></A>
<DIV ALIGN="CENTER">
<A NAME="1202"></A>
<TABLE CELLPADDING=3>
<CAPTION><STRONG>Table 2.1:</STRONG>
Matrix types in the LAPACK naming scheme</CAPTION>
<TR><TD ALIGN="LEFT">BD</TD>
<TD ALIGN="LEFT">bidiagonal</TD>
</TR>
<TR><TD ALIGN="LEFT">DI</TD>
<TD ALIGN="LEFT">diagonal</TD>
</TR>
<TR><TD ALIGN="LEFT">GB</TD>
<TD ALIGN="LEFT">general band</TD>
</TR>
<TR><TD ALIGN="LEFT">GE</TD>
<TD ALIGN="LEFT">general (i.e., unsymmetric, in some cases rectangular)</TD>
</TR>
<TR><TD ALIGN="LEFT">GG</TD>
<TD ALIGN="LEFT">general matrices, generalized problem (i.e., a pair of general matrices)</TD>
</TR>
<TR><TD ALIGN="LEFT">GT</TD>
<TD ALIGN="LEFT">general tridiagonal</TD>
</TR>
<TR><TD ALIGN="LEFT">HB</TD>
<TD ALIGN="LEFT">(complex) Hermitian band</TD>
</TR>
<TR><TD ALIGN="LEFT">HE</TD>
<TD ALIGN="LEFT">(complex) Hermitian</TD>
</TR>
<TR><TD ALIGN="LEFT">HG</TD>
<TD ALIGN="LEFT">upper Hessenberg matrix, generalized problem (i.e a Hessenberg and a</TD>
</TR>
<TR><TD ALIGN="LEFT">&nbsp;</TD>
<TD ALIGN="LEFT">triangular matrix)</TD>
</TR>
<TR><TD ALIGN="LEFT">HP</TD>
<TD ALIGN="LEFT">(complex) Hermitian, packed storage</TD>
</TR>
<TR><TD ALIGN="LEFT">HS</TD>
<TD ALIGN="LEFT">upper Hessenberg</TD>
</TR>
<TR><TD ALIGN="LEFT">OP</TD>
<TD ALIGN="LEFT">(real) orthogonal, packed storage</TD>
</TR>
<TR><TD ALIGN="LEFT">OR</TD>
<TD ALIGN="LEFT">(real) orthogonal</TD>
</TR>
<TR><TD ALIGN="LEFT">PB</TD>
<TD ALIGN="LEFT">symmetric or Hermitian positive definite band</TD>
</TR>
<TR><TD ALIGN="LEFT">PO</TD>
<TD ALIGN="LEFT">symmetric or Hermitian positive definite</TD>
</TR>
<TR><TD ALIGN="LEFT">PP</TD>
<TD ALIGN="LEFT">symmetric or Hermitian positive definite, packed storage</TD>
</TR>
<TR><TD ALIGN="LEFT">PT</TD>
<TD ALIGN="LEFT">symmetric or Hermitian positive definite tridiagonal</TD>
</TR>
<TR><TD ALIGN="LEFT">SB</TD>
<TD ALIGN="LEFT">(real) symmetric band</TD>
</TR>
<TR><TD ALIGN="LEFT">SP</TD>
<TD ALIGN="LEFT">symmetric, packed storage</TD>
</TR>
<TR><TD ALIGN="LEFT">ST</TD>
<TD ALIGN="LEFT">(real) symmetric tridiagonal</TD>
</TR>
<TR><TD ALIGN="LEFT">SY</TD>
<TD ALIGN="LEFT">symmetric</TD>
</TR>
<TR><TD ALIGN="LEFT">TB</TD>
<TD ALIGN="LEFT">triangular band</TD>
</TR>
<TR><TD ALIGN="LEFT">TG</TD>
<TD ALIGN="LEFT">triangular matrices, generalized problem (i.e., a pair of triangular matrices)</TD>
</TR>
<TR><TD ALIGN="LEFT">TP</TD>
<TD ALIGN="LEFT">triangular, packed storage</TD>
</TR>
<TR><TD ALIGN="LEFT">TR</TD>
<TD ALIGN="LEFT">triangular (or in some cases quasi-triangular)</TD>
</TR>
<TR><TD ALIGN="LEFT">TZ</TD>
<TD ALIGN="LEFT">trapezoidal</TD>
</TR>
<TR><TD ALIGN="LEFT">UN</TD>
<TD ALIGN="LEFT">(complex) unitary</TD>
</TR>
<TR><TD ALIGN="LEFT">UP</TD>
<TD ALIGN="LEFT">(complex) unitary, packed storage</TD>
</TR>
</TABLE>
</DIV>
</DIV>
<BR>

<P>
When we wish to refer to a class of routines that performs the
same function on different types of matrices, we replace the first three
letters by ``xyy''. Thus xyySVX refers to all the expert driver routines for
systems of linear equations that are listed in Table&nbsp;<A HREF="node26.html#tabdrivelineq">2.2</A>.

<P>
The last three letters <B>ZZZ</B> indicate the computation performed.
Their meanings will be explained in Section&nbsp;<A HREF="node37.html#seccomp">2.4</A>.
For example, SGEBRD is a single precision routine that performs a
bidiagonal reduction (BRD) of a real general matrix.

<P>
The names of auxiliary routines<A NAME="1213"></A> follow a
similar scheme except that the
2nd and 3rd characters YY are usually LA (for example, SLASCL
or CLARFG). There are two kinds of exception.
Auxiliary routines that implement an unblocked version of a block
algorithm have similar names to the routines that perform
the block algorithm, with the sixth character being ``2'' (for example,
SGETF2 is the unblocked version of SGETRF).
A few routines that may be
regarded as extensions to the BLAS are named according to the BLAS
naming schemes (for example, CROT, CSYR).

<P>
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<ADDRESS>
<I>Susan Blackford</I>
<BR><I>1999-10-01</I>
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